In a wireless communications network, a common application scenario is as follows: a first wireless device scans many other wireless devices to discover a second wireless device, a data connection is established and maintained between the first wireless device and the second wireless device, and when data needs to be transmitted, data transmission is performed. For example, a smart phone of a user may discover a smart watch by means of Bluetooth scan, and then a communication connection is established and maintained; when receiving an SMS message, the smart phone can send the SMS message to the watch so that the watch displays the SMS message.
Using a Bluetooth Low Energy (BLE) profile as an example, a wireless device discovery process involves different device roles and operation procedures thereof, which comprise:
1) A slave device role, which serves as an advertiser to execute a broadcasting process. In this period, a slave device keeps entering broadcasting events, as shown in FIG. 1. An interval period Ta exists between start times of neighboring broadcasting events, and the interval period consists of a broadcasting interval (advInterval) having a fixed length and a broadcasting delay (advDelay) of which the length is generated randomly. In a broadcasting event, the adviser separately sends packet data units (PDUs), namely, broadcasting packets, on broadcasting channels 37, 38, and 39.
2) A master device role, which serves as an initiator/scanner to execute an initiating/scan process. As shown in FIG. 2, the initiating/scan process comprises a scan interval (scanInterval) that appears repeatedly, where each interval comprises a scan window (scanWindow). In different scan windows, a radio frequency module of the master device listens on the broadcasting channels 37, 38, and 39, and receives a broadcasting PDU on a corresponding channel; outside the scan window, the master device performs regular scheduling, or turns off the radio frequency module. If the initiator/scanner receives a broadcasting PDU, it means that the master device successfully discovers a corresponding advertiser device. An initiator may directly send a connection request (CONN_REQ) to agree with an advertiser on information such as a time point for initial sending and receiving, an interval between different sending and receiving operations, and a frequency hopping channel and frequency hopping mode used, thereby establishing a connection. A scanner may send a scan request (SCAN_REQ), to require the advertiser to reply so as to provide more related information.
It can be seen that, a discovery process between wireless devices is a mutual probing process, which does not involve determining of a transmit power, and this is not favorable to reducing power consumption of communication between wireless devices.